Glare screen



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nventorg )Qaa 7.1 nee attornegg Patented Apr. 28, 1953 GLARE SCREEN Joseph D. Ryan and Paul T. Mattimoe, Toledo,V "Ghio, assignors to Libbey-Owens-Ford Glass rompany, Toledo, Ohioa corporationrof Ohio Y Application'Noveniber 18, 1948, Serial'No. 60,725

'The present invention relates generally toglare sci-eens, Aand more vparticularly to a novel type of laminated safety glass window, windshield or the -like that is provided With a built-in glarere'clucing portion.

Briefly stated, this invention contemplates a laminated safety glass lunit which includes a ',non-)brittlefplastic interlayer having a colored or neutral shaded glare-reducing portion which is ,preferably of a shade .graduated from deep 'or opagueat one side of its area to practical extinctionat anothen'laxninated with one or more .sheets of .glass which have a relatively high ihlmlnous transmittance in the visible region of .thespectrum but have relatively low ultra-violet light Ltransrnittance.

.'I'he` article o'f the invention has particular utility when employedas a vvindovv or windshield `iin vehicles, or'in other ,places where the elimina- `,tion or reduction of glare from the sun or objjectionably Lhright artificial light is desirable. The .importance of reducing glare through the window and windshields .of Apassenger automohiles, buses, .railroad trains, and aircraft of `all `kinds has, `of course, long been recognized, and 4,great deal of Work has been done in attempting to kprovide adequate and satisfactory glare-reiducing vmeans.` for this purpose.

.Probab1y,the greatest proportion of this Work has been concentrated on the reductionof glare through the windshields of automobiles, "rst, because clear visionthroughthe Windshield is of utmost .importance and, second, because it is .from -ithe windshield that both `drivers and pas- ,.sengersare mostlikely tobe inconvenienced and made uncomfortable .by glare, not only fromy directvand releetedrays of. the sun, but also from the headlights of oncoming vehicles, and so forth.

-Moreover, Ythe `trend in present day automotive design is toward ever increasing Window areasfin automobiles Vandin .the oase of Windtshieldsin particular, the tendency is not only to .make them Wider, but higher as well, and to carry Athem farther and Vfarther into what Was formerly considered to .be the roof area of the car. Such modern, streamlined, and rather revolutionary designing presents new and much more difficult problems from the standpoint of glare, and renders known glare-reducing means virtually obsolete land ofv minimum `practical value. For example, the familiar cloth Visors now Widely used lin "automobiles `nare not practicable for the Anevv typevvindshields Moreover, such Visors are unsatisfactory because `of their complete opacity andthe Af a'ct't'hai'. they lcut'oii'alange share ofthe 2 Claims. (Cl. 88-108) 2 drivers vision when in operative position and make it impossible for him to see stop ilights Without peering around or under the visor.

Now, it is an aim of the present invention to `provide a special type of laminated safety glass unit, having an integral glare-reducing portion of a special type, for use as a window or .windshield, and which lends itself readily to even the most extreme, modern, automotive designs.

Another object is the provision ofra unit of the `above character in which at least a portion of the -not be overemphasized since experience has shown that an internal visor of uniform shade with `sharp cut-01T between low and high light transmitting areas is most distracting -to the operator of a vehicle.

Not only does fatigue resuit because of the rapid rate of eye 'accommodation required in shifting of the eye from a low levelof illumination to a high level, but distracytion results from the rapid rate -of Vshift of the sharp cut-ofi as the vehicle, and particularly yan automobile, responds to unevenness of the `high- Way. Another extremely bothersome factor Yarising from a sharp `cut-oir is the failure to yproperly provide for height diierences of individuals operating a vehicle. Thus, a visor appropriate for a shorter individual is totally unsuited for -a taller one, since his eye level line `is too high, requiring ducking of the head for easy operation.

Another object is the provision of a light stable, antiglare Window or Windshield of this same general Vcharacter in which the glare-eliminating or reducing portion of the unit is produced by dyeing the plastic interlayer prior to laminating it together with the glass.

Still another object is the provision in such a unit of a glass sheet or sheets of a character which absorb or otherwise reduce the transmission of objectionable light rays into and through the unit, and which have antiglare properties of their own.

Other objects and advantages of the 'invention VWillbecorne more apparent during the course of :section of the dyeing apparatus;

the following description, when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

Fig. 1 is a fragmentary perspective View of an automobile having a windshield produced in -accordance with the invention; f

Fig. 2 is a fragmentary section taken substantially on the line 2-2 in Fig. 1;

Fig. 3 is a side elevation of the dyeing apparatus of the invention;

Fig. 4 is a vertical transverse sectional view taken substantially on the line 4 4 in Fig. 3;

Fig. 5 is a fragmentary plan view of the transfer rails over which the plastic sheets are conveyed through the dyeing apparatus;

Fig. 6 is a vertical transverse section taken on the line 6-6 in Fig. 3, showing the first rinsing Fig. 7 is a perspective view of some of the spraying elements for rinsing the plastic sheets; Fig. 8 is a perspective view of a dipping frame showing a sheet of plastic attached Ialong its perimeter;

, Fig.` 9 is a partial longitudinal section of the vdyeing apparatus and, more particularly, of the rst and second rinsing sections;

Fig.V 10 isan end view of the dyeing apparatus, Athe rinsing head being shown raised, as at entry of plastic sheets;

Fig. 11 is aY fragmentary side view of the end of the apparatus,` the rinsing head being positioned at the lower'extremity of its movement.

s Also illustrated-therein is the locking device for -retaining said `head ina position substantially as vshown in Fig. 10; f

v.in assembling them together into a sandwich -prior to laminating;

Figs. 15, 16 17 and 18 are graphic illustrations of light transmission curves for the colored or shaded areas of four windshields having differently dyed plastic interlayers;

Fig. 19 is a curve showing the eiect of immersion time on the depth of coloration in the -dyed plastic;

Fig. 20 is a Icurve showing the eiiect of immersion temperatures on the depth of coloration in the dyed plastic;

Fig. 21 is a curve showing the effect of dye `concentration on the depth of coloration in the dyed plastic; and

Fig. 22 is a graphic illustration of two curves, 'showing the effect of the solvent composition rused in dissolving the dye on the depth of coloration in the dyed plastic.

Referring now more particularly to the drawings, it will be noted that the automobile shown Yin Fig. 1 has large window areas, and that the windshield Ill-extends upwardly to a greater extent than heretofore, and'is bent so as to actually form the forward roof portion of the car. This type of design provides an extremely wide frange of vision for the occupants of the vehicle and opens up the field of vision from the car for greater enjoyment of the driver and passengers at most hours of the day and night.

One very important disadvantage of this design, however, though it may be 'only occasional, is that rays of the sun, even when at a very steep angle, may pass through the windshield. Or, differently expressed, when the sun is only slightly past its zenith, vit may shine through a windshield of this design when the car is traveling toward the sun. For that matter, similar diculty is encountered, even with flat glass windshields, when set at the angle common to most present day automotive designs.

This is of course undesirable, because of the elTect of the direct and reflected glare, from light shining on the windshield, on the eyes of the front seat occupants, and also because of the heat that is brought into the car in this way.

Attempts have recently been made to overcome this di'iculty by providing opaque sun Visors projecting outwardly over the windshield and at an angle thereto; and, in some cases, over the doors. However, while these effectively cut off the rays of the sun, they also defeat the primary purpose ofthe wide view windshield design. In addition, they are open to all of the objections to an extra accessory that juts out from the main body of the automobile, ruining streamlining and cutting down speed. (Actual tests show that such Visors will cut down car speeds as much as 5 to 10 miles per hour.) Moreover, overhead sto-p lights and danger signals can not be seen through them and manufacturers of these visors have gone so far as to suggest the use of prism reflectors in cars equipped with them to overcome this serious disadvantage.

Now we have found that this problem of glare can be effectively solved in an entirely different way, by the provision of an antiglare means that forms an integral part of the laminated safety glass of the windshield and will cut outthe objectionable rays without materially aifecting desired visibility through the glass.

We do this primarily by governing, by gradation, the amount of light permitted to enter through a given area of the windshield, thus giving light where needed without blinding the occupants and, at the same time, -cutting out light where this is desirable while permitting adequate vision wherever necessary.

As shown in Fig. 1, in a preferred form, the antiglare means of the invention is a color or neutral shading Il within the windshield itself, and is vignetted or graduated in shade from a deep hue at I@ along the top margin of the windshield, which may be opaque, or nearly opaque, to a very light hue I3 in the area adjacent the essential viewing area I4 of the driver and through which he sees the road and oncoming traffic. ,y l

The advantage of this arrangement will be immediately apparent. Thus, the depth of hue vor color or shade, and consequently the glarekgradually increased as he shifts his line of sight 70.

. toward the area ofpotentially greatest glare. .a Lfurther advantage is that the observers eyes 7. 'red'sz is threaded inte a link 55 piveteuy attached. 3 to the slide plate 41 by a pin 56 while to the outer' end of the rod 53 a clevis 51 is threadably at tached. The clevis 51 is drilled to receive pins 58 which are inserted through the ends of arms 531 and and the adjoining sides of the clevis. The arms 59 and 5| are journaled, so as to revolve, in. bearings 59 mounted on columns 60 of the frame I8. More particularly, the arms 59 and 5| each. have a centrally disposed tubular portion 3| from which extends here s2, es and a4, the par e2 ef4 each arm being related, at its outer end, to the clevis 51 by the pin 58. f

As best illustrated in Fig. 5, the bars 63 and 64- of each arm are interconnected at their outer ends by a rod 65, the projecting ends of which are journalled in bearings 66 secured to the up-l wardly extended posts 4U of the framework 38. Thus, as the slide plate 41 moves upwardly, the arms 59 and 5| will revolve on their respectivebearings 59 and tilt from the positions indicated in phantom line (Fig. 4) to the position shown in full lines, in which position the carriage 23 is at the lowest point of the dipping stroke. Downward movement of the slide plate inversely pro duces upward motion of the framework or removal of the plastic sheets from the dyeing solution 43 contained within the vat 44.

Movement of the slide plate, in either direction, is designed to effect rapid, partial 'descent of thecarriage 23 and the plastic sheets 22, suspended. therefrom, subsequent descent controlled by the surface of a cam 811 and after a predetermined. time period, rapid elevation to quickly remove thesaid sheets. tial phases of operation is achieved by the opera-- tion of geared units which are mechanically related to the slide plate 41. Thus, the geared unit 88 operates a linkage 69 comprising arms 19 and 1|, the arm 19being keyed to the shaft 12 of the unit 88 and pivotally connected to the arm 1| by a pin 13. vThe arm 1| is slotted, as indicated at 14, to permit free movement of a stud 'i5 therein upon movement of the stud by the slide plate 41 in which said stud is xedly secured.

Motion of the slide plate is caused by the pull exerted by weight of the carriage 23 through the arms 59 an-d 5| and compound rod 49. Howl ever, when the carriage 23 is received on the framework 38, the effect of such a weight force is offset by a resistance established in the unit 68, the brake of its, drive motor and the drive belt thereof. Operation of the unit 33 thus createsva mechanical counterbalance and during a portion of such operation affords a control for descent of the framework 38 and carriage 23. When the arm of the linkage 69 has completed substantially a half revolution, the slideplate is raised sunciently to place it in the control surface area of the cam 61. The cam is engaged by a rollel` 16 carried by the plate 1| near its lower end by a stud 11.

Through electrical controls (not shown) the unit 68 is now rendered inoperative and a similar gear drive, indicated at 18, is started. The cam 31 is secured to a face plate 19 keyed to the output shaft of the unit 18 and the influence afforded during its rotation is determined by the Vcarri areas of its surface. The roller 13 thus rides 1 on the cam surface which gradually permits rising of the slide plate within slide or guideways 89 secured to the main structure I8. The .timing cycle of the dipping produces thegraded area of the plastic sheets and consequently variously .generated cam surfaces may be employedto se- Accomp-lishment of these seduen-l .y

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lectively control the extent and the time period to which the plastic sheets are further immersed into the vat 44 and the solution 46 contained therein.

Accordingly, the lowest point in descent of the sheets may be established and when this point is reached, it is desirable to rapidly raise the carriage. Adequately positioned controls are now eiectedto resume operation of the unit 68 and, through the linkage 48, to engage the stud 15 by an end of the slot 14 in the arm 1 I. Rotation of the shaft 12 to complete a full revolution `of the arm 10 of said linkageGS produces con- :sequent separation of the roller 18 from the .surface of the cam 61 and delivery of the slide j-plate 41 to the lower extremity of its travel. Through the rod 49 and arms 50 and 5I, this movement of the plate 41 is transmitted to the framework 38 to raise it and the carriage 23 to a point where the rails 4| and 42 on the elevator framework are again in alignment with the rails 33 and 34 of the loading and rinsing sections.`

Immediately upon lcompletion of the dyeing cycle, the carriage 23 is propelled toward the rinsing sections D and E and, as it moves out of the dipping section C, the wheels 43 ride off the rails 4I and 42 on the elevator while the wheels 35 ride onto the section of the rails 33 and 34 leading to the rinsing sections. The manner in which the wheels 43 leave the rails 4| and 42 while the wheels 35 engage the rails 33 and 34 is best shown in Fig. 5.

As the plastic sheets on the carriage 23 move into the rst rinse section D, they are immediately subjected to an alcohol rinse by means of spray pipes. 8|. The pipes 8l are arranged in pairs along a manifold pipe 82 and their ends are suitably flattened and bent, as at 83, to direct the alcohol against the opposed surfaces of adjacent sheets. .Pretend-bly, the spray pipes 8| are of suflicient height to present the alcohol in areas along and above the areas of the plastic sheets which have been affected by the dyeing solution. As shown in Fig. 9, the manifold pipe 82 is supported in carriages 84 which traverse rails and 86, horizontally disposed along and above the sides of a receiving tank 81. The tank or tray 81 is supported on the angles 88 and'is Aconnected to a usual sump by the pipe 89.

The carriages 84 are supported by wheels 90 on the rails 85 and 86 and are propelled by chain belts 9|, driven by a crank 92 and trained over sprocket gears 93 and 94. I'he sprocket gear 93, lconstituting the driver for the belts 9| is keyed to a shaft 95 journaled in bearings 96 and extending through the rails 85 and 86. Ordinarily, one pass of the pipes 8| will produce the desired .rinsing effect on the plastic sheets and the dyed areas thereof; however, if further rinsing is found necessary, rotation of the crank 92 in the opposite direction will return the carriages 84 to a position substantially as shown in Fig. 3.

The alcohol is delivered to the manifold pipe 82 from a supply pipe 91, through a length of flexible tubing 98 and suitable ttings 99.

From the rst rinse area D, the carriage 23 is propelled along the rails 33 and 34 until it and the suspended plastic sheets 22 are positioned above the tank or tray |00 of the second rinsing area E. .The arrangement of the tanks 81 and |09, as seen in Fig. 9, prevents dripping of the 4escaping rinse as the carriage is moved from one rinse area to the adjoining area. Preferably,

.in the second rinsing area for the plastic sheets 9 provision is made for rinsing said sheets with water and subsequently with` distilled water or condensate.

According'to the desired arrangement of water rinsing, the distilled water is pumped into a pipe supplying system in a manner that either can be independently directed to the head This head, as shown in Figs. 9 and 10 and indicated by the numeral |0|, comprises a plurality of horizontally disposed pipes |02 having spray orifices |03 drilled therein. Preferably, the orifices are located diametrically opposite in the wall of eachof the pipes with the exception of the outermost pipe ateach side. Necessarily, the orifices of these pipes are provided in one wall only. The pipes |02 are connected as by weldingV to amanifold pipe |0fl which in'turn is welded toa vertically extending pipe |05. The pipe or standard m5 jointly-serves as a conduit and as a slide member by which the head- |0| generally is raised or lowered with reference to the tank |00, the frame I8 of the apparatus, or the plastic sheets 22.

As illustrated in Figs. 6 and lo, the pipes |62 are arranged to direct the water rinse toward opposed surfaces of the-adjoining sheets in areas wellabove the dyeareavto createa uniformooding of the sheets as the water descends on the surfaces. The head |0| is also designed so that the maximum height ofthe pipes |02 may be adjustedaccording to the widthcf the dyed area. in ordinary operation, the height of the pipes, as shown in Fig. 9, has beenVv found to be satisfactory for starting the second rinsing as the carriage is propelled to deliver the plastic sheets between the plurality of spray pipes |02. Once the carriage is stopped, the head lill is moved downwardly so` that the rinsing effect of the Water continues until the pipes |02 are carried well beneath the frames 21;

The head |0| moves vertically through a path established by a block or collar |06 through which the pipe |05 passes. The collar is supported within and forms a part of the bracket |01' secured to the apparatus frame structure. Beneath the bracket |0l, thepipe |05 is clamped between blocks |08 and |09, each of said blocks having inner surfaces contoured to receive the pipe. To securely clamp said' pipe, bolts ||0 are extended through the block |08 and threaded into the block |09 which is fixedly secured to the angle ill comprising in part a traversing carriage H2 for the head |0|. The angle extends transversely of the frame structure |8 and substantially along the outer surfaces of the legs |23 thereof.

Blocks le are secured at the ends of the angle lll; said blocks having angularly formed surfaces H5 which cooperate with surfaces ||6 of latches lll. When the carriage is raised, and near the top of its movement to position the pipes m2 as shown in Fig. 10, the cooperating surfaces lib and llt produce deflection of the latches until 'the lower surfaces of the blocks lill can be engaged by the latches i |71 to Vretain the head Il generally in its elevated position. The latches are carried by a cross shaft HB journaled inthe legs H3 and are urged in one direction to engage the blocks Htl by a spring N9 extended between one or said latches and a plate |20 attached to the adjacent leg H3.

if, desired, -a thandle |2| may be amxed to the block |08 in order that `the carriage `canfbe manipulated manuallyin either direction during therinsing-operation. Also, to'balance the 'carriage andV assure its descent with an evenness of movement, a weight |22 is connected to the carriage by cables |23 which are trained over pairs of pulleys |24l and |25. One means of attaching the cables tothe carriage is shown in detail in Fig. 12 wherein will be seen a bracket |26 secured to angle said, bracket having suitable clamping blocks lil for gripping one end of the cable.

The pairs of pulleys |24 and |225 are arranged beneath the tank |00, as shown in Fig. 9, and pivotally supported on brackets |23 attached to the angles le of the framing structure i0. As shown therein, each of the cables is trained over a pulley |24 to the pulley |25 and downwardly to clamps |29 forming a part of the Weight |22.

When the head l0! is to be lowered, either of the latches l is engaged by its projecting handle to release the blocks l I4 and accordingly the carriage H2. During the descending movement of the head |0|, the spray of water from the pipes |02 will be directed against the surfaces of the sheets 22 and in running therefrom will be gathered in the tank |00 and discharged to a suitable drain through the pipe me.

As previously indicated, it has been found advantageous to rinse the plastic sheets with ordinary city main water and subsequently with distilled water or condensate. Such an arrangement is conventionally shown in Fig. 3, wherein the distilled water is supplied from the pipe |3| while pipe |32 supplies ordinary main water, each of said pipes having suitable valves for governing the rate of flow. The supply ipe lill extends to a reservoir tank |33 which is connected by a pipe |311` to a motor operated pump |35. The pump outlet is connected by a conduit Kl to a fitting located in the pipe |32. The extending end of said pipe |32 is then connected to the vertical pipe ofthe head |0| by usual fittings i3? and a flexible section of hose i3d;

Thus, when first rinsing the sheets 22, the pump |35- is inoperative and city water through pipe |32 is supplied to thehead llll by the hose |38. Following this rinsing, the valve in the pipe |32 is closed and the head raised to its original upper position. The pump |35 is then started and distilled; Water will be withdrawn from the reservoir |33` by `the pipe |34, the pump, and through the conduit lli to the flexible hose section |38 so that as thehead lili is subsequently lowered, distilled water, or condensate, will be directed against the plastic sheets in a final rinsing operation.

Upon completion of the second rinsing operation, the frames 27 and attached sheets of plastic 22 are removed from the hook bolts 2E, and removed to a drying area. When the carriage 23 is emptied of frames, it can be removed to the loading station B oflthe apparatus and the spray head HH' returned to its elevated position for subsequent use.

In employing the apparatus just described to practice our invention, we first fill the vat de' with a Vsuitable dye solution. We lprefer to employ dyes of a color or shade that are soft and pleasing to the eye, that permit objects to be observed through them with a minimum of distortion to their appearance, and through which primary `colors suchas the red, green and amber of traffic lights are readily distinguishable.

There are a number .of dyes that have such desirable characteristics, but we prefer dyes that also have recognized better than average light stability, Vand stabiiityto heat at the temperatures required to bond glass and plastic interlayers together.

Examples of such dyes are:

The sodium salt of 1:4 bis ortho-sulpho-paratolyl aminoanthraquinone (Color Index No. 1078), sometimes known in the trade as Alizarin Cyanone Green G Exg the sodium salt of monosulpho 1:4 bis para-tolyl aminoanthraquinone, commonly called Alizarin Cyanone Green Gl\l; Du Pont Orange II conc. (Color Index No. 151) Du Pont Chromacyl Black W; Alizarin Fast Blue RB; Alizarin Violet NRR; Acetamine Black CBS; and Du Pont Nigrosine Base (Color Index No. 864).

After selection of the dye, it is necessary to make up the dye solution. As illustrative of our procedure, in using the sodium salt of 1:4rbis ortho-sulpho-para-tolyl aminoanthraquinone, hereinafter referred to as Alizarin Cyanone Green G Ex dye, we prepare a dye solution by merging into nothingness at the fade-outer cutoff point.

The advantage of the latterarrangement is that it may be desirable to provide relatively wide areas of substantially uniform hue in certain parts of the colored or shaded area. For example, in a windshield which is bent upwardly over the heads of the front seat occupants, it may be advisable to have a relatively wide band of .the darkest hue in that part that is exposed to the direct rays of the sun from overhead.

In order to set the controls to obtain these desired results, it is necessary that a definite schedule for graduated immersion of the plastic in the dye solution be established, and this schedule will depend on the particular shaded eect to be dissolving about 2% of this dye in a 50% by volume mixture of aqueous denatured alcohol. While solution can be accomplished in many ways, one method is to prepare the solution by heating 400 grams of the dye to reux temperature in 10 liters of Formula I denatured alcohol (95% ethanol-5% methanol) with stirring, diluting with l0 liters of distilled water and then filtering.

The spectral transmittance of this dye is shown by the curve in Fig. 13.

Other solvents for the dye, such as water, methanol water mixtures, isopropanol water mixtures, etc., may be satisfactorily employed. The main object is to bring the dye into solution using mixtures which will not too rapidly attack the plastic to be dyed during the time and temperature cycle to be used.

When the vat 44 has been lled with the desired dye solution, a group of plastic sheets cut to the required size are fixed to the frame 21. These plastic sheets arel preferably cut oversize to permit attachment to the frames and to allow for subsequent orientation when assembling the dyed plastic with the glass sheets. A carriage 23, positioned Within the loading section B, is then hung with a capacity load of frames 21 to which the plastic sheets to be dyed have been amxed. The full carriage is then moved from the loading station B onto the elevator 3l in the dipping section C.

The dyeing treatment is applicable to any of the commonly used synthetic resin, laminated safety glass plastics, such as polyvinyl butyral resin sheeting plasticized with 41 parts dibutyl cellosolve adipate, now used by the assignee company, or when plasticized with other suitable plasticizers such as dibutyl sebacate, triethylene glycol dihexoate (commonly called B-GI-I) or a mixture of triethylene glycol caprate and triethylene glycol caprylate (known to the art as J-24).

As explained above, by employing a cam of the proper shape, and by proper control of its driven speed, the plastic sheets can be immersed in the dye solution 46 in a manner to produce an even shade over the entire area to be dyed. Or, the margin of the plastic sheets may be shaded gradually and uniformly from a deep hue at the edge to color extinction at the fade-olf point. Or, the desired vignetted eiiect can be obtained by a series of bands with adjacent bands being of graduated intensity from a deep hued band at the plastic edge to a graduated light hued band produced.

In immersing the plastic in the dye, it is best to move the elevator 31, carrying the carriage 23, rapidly downward to a predetermined indexing point, at which point the lower edges of the frames 21 are in the dye and the main body of the plastic is about to be immersed. From this point on, any immersion schedule which will give the desired vignetted effect can be used.

For example, by dyeing plastic sheets in accordance with the following immersion schedule, using the Alizarin Cyanone Green G Ex dye solution described above, and then laminating them as interlayers between two sheets of special glass to be hereinafter described, finished windshields having the transmission curve shown in Fig. 15, will be produced:

Immersion schedule I Temperature of dye 97 F. This will give a continuous fade-off.

Other dyed plastic sheets having a continuous fade-off, that is proportional to the distancel can be obtained by immersing the sheets according to the following schedule with the dye bath at a temperature of 97 F.:

Immersion schedule II Rate of Immersion, Inches Time, No. Dlstance Total Dls' per Minute of Minutes gles tfnlg' Dyed plastic sheets having a 2 in. wide, constant transmission band at one margin, and a continuous fade-off from this band can be obltainedby immersing the sheets according tothe I3 following schedule with the d'ye bath at a telnnerature ofi 92' F.:

Immersion schedule III' Rateof Immersion inchesk Time, No. Dlance Total Dls No. tance, No. per Minute of Minutes Inches of Inches) `0,4 .0. 5A .2.0 1.3, 0.5, 2.5` 1. 7' 0. 5 3. 0 1; 1 0. 5v 3. 5 0. 63 0. 333 3. 833 0. 40 0. 333 4; 166 0. 25 0. 333 4; 49.9 0. 22 0. 500, i 5. 00

Plastic sheets having a. dyed area of inches with approximatelyV a 3 in. constant transmis'- zsion band at one margin and a continuous fadeoifrom this band can be obtained' by immersing the sheets according` to the following schedule in adye'bath at a temperature of 9'?"l F;

Upon completion of the dipping cycle, according to the desi-red immersion schedule, the elevator 31 is raised to Withdraw the plastic sheets .from the dyeing bath as rapidly as possible and the carriage `23 is then `quickly moved, rst into `the first rinsing section D where the dyed pori tion of the` `sheet is immediately rinsed with a mixture of 50% denaturedethan (95% ethanol 5% methanol) and 501% by volume of distilled water to remove the dyeing` solution from the plastic and to` arrest the dyeing action, and then `.into the second rinsing section D Where it is :rinsed with water.

.'Ivvov of the steps of our dyeing procedure Which are of special importance in producing an accurately controlled intensity in the colored or lshaded. area of the dyed plastic and in maintainthe area free of streaks and other irregular rcolor variations are: (l) the particular dipping procedure that We use, and (2) the special rinsing technique.

fshus, it win be noted that we do not dip tile plastic by firsty immersing the entire area. to be -colored and then slowly withdrawing it from the bath, but that, instead, We immerse the area to `The shaded slowly andvprogressively into the dyeing 'bath untilF the `desired area .has been immersed and then quickly withdraw the plastic from thebath. This reduces to a minimum the time during which the free dye solution onl the `plastic can run .down over the dyed area.

` `This also permits the removal o1v all parts of the `dyed area from lthe bath just as soon as they `havebeen in contact with the dye solution 4for T4 ldyed area immediately after ithasbeen-removed from the bath.

We have found that the composition of the rinse usedafter the dye bath will depend upon the solvent composition ofthe dyefbath, but that in general mixtures of various water-soluble alcohol-Water mixtures are most. suitable for producing an imperceptible fade-ofi from the dyed to the undyed areas.

This israther surprising because actually the dyes we have used aremore soluble in water than in alcohol. Nevertheless. when` the. dyed area is rinsed first With Water, a sharp cut-off lineI results after drying. On the other hand, when the dyed area is rinsed with alcohol first, the cut-oit is much less perceptible andthedyedarea blends much more smoothly into the undyed area.

After rinsing, the dyed plastic must be dried. This is most important since considerable quan- "tities of solvents from theA dye bath (even up: to

25% of' the weight of the dipped area of the sheet) may be absorbed during the dyeing process. Actually, all ofy thesesol-vents and/or water must be removed before theI laminating step since not more than .5% can-remain if satisfactory adhesion `and heat stability (failure to bubble in service) isto be attained.

The plastic therefore is dried on the frame, preferably in an oven at F. to accomplish solvent and/or water removal. Other means, such as by leaching in non-solvents for the plastic which are solvents for the dye bathA constituents, may be employed as apreliminary step to oven drying; We have` found that it is desirable in some cases toA preliminarily dry the plasticfor a short time. until tack free, inaclean, dirt and .dust free oven, and then, finish drying after dusting the surface: with a. salt` such as finely divided sodium bicarbonate. This insures that dirt falling on the plastic during thedrying period' will be removed in the subsequent plastic WashingV operation.

After washing, the plastic (moisture and' sclvent content 'below/0.5% by Weight)` is `then ready for assembly and laminating together'wit-h the glass sheets.

Now we have .discoveredr that the completed unit will have much .greater light stability,` and better ant-iglare` properties ifsaprotective type of glass is used with the dyed plastics. There are -a `number of glasses of this general .type that will give satisfactfny results, the most important properties required `being `.that they transmitI a relatively high percentage .ovisible light while, `at the same time, cutting yolii a relatively high percent of theultra-violet light.

We have found that glassesy intended primarily vfor heat absorption, glass. intended primarily for `absorb as Amuch las 34% of ultraviolet light, the `dyed area will not fade in normal use. have also found that when such glass transmits And -we as much as '10% of visible light it can be satis.- factorily used i-n glazingsight openings such as windshields under the American Standards Asthe required length vof time. And we rinse 'the T5 sociation 00de.

n the tables below, .we have listed six different representative types of glasses which have proved satisfactory for our purpose:

' i Type A Type B Type C Type D Type E Type F Types A and F areheat absorbing glasses, type Bis a golden colored glass,type C is a blue-green colored glass, and types D and E areother special protective glasses. These glasses have the following average transmittances: y l

. Transmittances-Percent Glass Thick.v

' Total U. V. Ill. A lll. C I. R. Rad' 112 63.5 82.0 83.3 37. 9 57. 4 109 2. 6 86. 8 85.6 90. 6 82. 5 lll 60. 7 82. 7 83. 7 55. 2 67.0 119 65. 7 85. 9 86. 5 67. 1 74. 8 l2() 67. 3 84. 7 85. 4 54. 7 67.3 111 42. l 75. 7 17. 1 29. 3 49. 1

Preparatory to laminating, the dyed plastic I1, after being lcut from the frame, isfassembled with two sheets of any one of the protective glasses listed above, or with any glass having similar ultra-violet absorbing" and visible light transmitting properties, as shown in Fig. 14. Alternately, it may be assembled with only one sheet of protective glass, as the outside sheet,`and one sheet of ordinary non-protective type glass as the inside sheet.

The glass sheets are preferably cut to size, and bent when necessary, prior to assembly with the plastic, but the plastic is preferably provided in oversize block pattern and cut to size after- Wards. W'hen this isdone, the edges of the plastic interlayer will extend past the edges of the glass as shown at |39 in Fig. 14, and this permits the dyed area of the plastic to be accurately positioned relative to the glass.

We wish to emphasize that it is important that the dyed portions be so positioned in different units that the cut-off line of the shaded or colored portions is in alignment in the right and left hand halves of the two-piece Windshield I0, When a two-piece windshield is used. Moreover, it may be desired toposition the plastic so that the cut-off line is parallel with the horizon in some cases, `or parallel with the top of the windshield in others. Also, the desired positioning of the f colored portionsA of the windshield may diier 'with different makes, styles or models of cars.

' After the glass sheets I5 and I6 and plastic yinterlayer l1 have been assembled in the manner outlined above toform a glass-plastic sandwich, the assembled unit. is laminated by any of the -standard laminating procedures to securely bond the several laminations into a unitary structure.

When units, using plastic interlayers dyedwith Alizarin Cyanone Green G Ex .dye-solution. ,as

Cil

described in ydetailin IImmersion schedules I,I I, III, andv IV above, and two' sheets of type C protective glass, are made up vinto wi'ndshields, the windshields will be provided with an integral, built-in antiglare screen which extends from the top edge thereof downwardly for a distance of about 5 inches, and will have a visible light transmission respectively as shown in Figs. 15, 16, 17 and 18.

In other words, the colored portion of the windshields will be graduated from -a relatively deep, dense greenshade at the top to a very light green shade toward the middle, and will have a barely discernible cut-off line at the bottom of the colored area.

To our surprise, we found that the manner in which the color varies from dark to light, theV extent of the colored area, the overall depth of color and the color at any one of several points can be-varied by controlling .the vtemperature of the dye solution, the solvent or solvent mixtures used, the concentration ofdye, and the time and speed of the immersion schedule.

In fact, so far as we can nd there Vis no literature dealing with the dyeing of plastics and for this reason we have set forth here complete information gained from our own work that will enable others to adequately practice our invention.

Thusin our studies of dyeing plastics, we have found that a number of important factors must be governed, namely, time of contact with the dye solution, concentration of the dyey in the solution, ratio of solvents used for the dye solution, make-up or type of solvent used as well as the temperature of the dye bath.

Considering these factors separately, in general as the time of immersion of the plastic in the dye bath is increased the deeper the coloration, although depth of color or lowering of light transmission is not directly proportional to time keeping other factors constant. This point is illustrated by the curve shown in Fig. 19.

N-ow if time of plastic immersion in the dye bath is kept constant, We have found that `depth of color or lowering of light transmission is greatly influenced by temperature keeping dye concentration and the solvent constant. To illustrate, see the curves of Fig. 20. l

If again temperature is maintained constant, the solvent mixture for the dye maintained'uniform in composition as well as the time, the depth of color of the plastic or lowering of-light transmission is influenced greatly by dye concentration within the limits of solubility of the dye in the dye bath. See curve of ',Fig. 21 attached.

We have further found that maintaining temperature of the dye bath constant, the concentration of dye constant, and the time of immersion constant, that the depth vof coloration of the plastic or lowering of light `transmission is affected by the solvent composition used in dissolving the dye. To illustrate, we have here'employed mixtures of water-denatured alcohol or isopropanol which, as seen from the curve in 7fiig. 22, influences color depth.

As pointed out heretofore, prior to our discovery, We were told by several leading plastic manufacturers that it was practically impossible to produce the colored plastic of oury invention at a commercially feasible price, and it was emphasized by the dye makers that even if produced such plastics would not be suiciently light stable for automotive use.

lHowever,` contrary Hto these opinions `*of experts in the plastic art, we have exposed units made in accordance with this invention to radiations from a quartav mercury arc lamp, according to the standard American Standards Association Code test for light stability for laminated safety glass, for over 500 hours, which is the equivalent of from 4 to 5 years actual service in an automobile, with no noticeable fading of the colored plastic; and further we have found that the cost of producing one of our units is only slightly greater than the cost of producing a similar 1aminated safety glass unit without the built-in antiglare screen.

Although our glare-reducing unit is especially valuable for use in glazing automobiles, aircraft and similar vehicles, it Will be appreciated that it has many other potential uses as well; and in lieu of laminating the shaded or colored plastic with two sheets of protective glass, we may also laminate it with a single layer of such glass. Or, it may be incorporated into a unit including more than two sheets of glass and more than one plastic interlayer and/or, in some cases, with an air space between adjacent glass sheets.

In fact, it is to be understood that the form of the invention herewith shown and described is to be taken as a preferred embodiment of the same, but that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

We claim:

1. A window having a built-in glare screen and comprising in combination a sheet of thermoplastic material having a colored area of gradually decreasing light transmission from an edge of said sheet toward the middle thereof, and a sheet of a soda-lme-silica glass of substantially the following composition:

Per cent SOz 72.06 A1203 .33 F6203 .50 TiOz .032 CaO 11.18 MgO 2.10 NazO 13.6 S03 .20 C0304 .00112 bonded to said plastic sheet on the side thereof that is toward the outside of the window.

2. A window having a built-in glare screen and comprising in combination a sheet of thermoplasmaterial having a colored area of gradually .decreasing light transmission from an edge of said sheet toward the middle thereof, and a sheet of soda-lime-silica glass of substantially the following composition:

Pei1 cent S102 71.08 72.41 A1203 .17 .48 Iron oxides .30 .559 T102 .013- .032 CaO 9.11 12.93 MgO .05 4.51 Naz() 13.13 -14.19 S03 .14 .38 C0304 0. .00112 bonded to said plastic sheet on the side thereof that is toward the outside of said window.

JOSEPH D. RYAN. PAUL T. MATTIMOE.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 970,111 Ramstein-Gschwind Sept 13, 1910 1,790,010 Lewis Jan. 27, 1931 1,805,969 Bostrom May 19, 1931 1,809,991 Stevens June 16, 1931 1,924,752 Rising Aug. 29, 1933 1,990,143 Snow Feb. 5, 1935 2,008,347 Boots July 16, 1935 2,303,732 White Jan. 19, 1943 2,370,697 Tillyer Mar, 6, 1945 2,461,612 Olpin et al Feb. 15, 1949 2,524,719 Tillyer Oct. 3, 1950 

2. A WINDOW HAVING A BUILT-IN GLARE SCREEN AND COMPRISING IN COMBINATION A SHEET OF THERMOPLASTIC MATERIAL HAVING A COLORED AREA OF GRDUALLY DECREASING LIGHT TRANSMISSION FROM AN EDGE OF SAID SHEET TOWARD THE MIDDLE THEREOF, AND A SHEET OF SODA-LIME-SILICA GLASS OF SUBSTANTIALLY THE FOLDLOWING COMPOSITION: BONDED TO SAID PLASTIC SHEET ON THE SIDE THEREOF THAT IS TOWARD THE OUTSIDE OF SAID WINDOW. 